Research On Short-term Cascade Reservoirs Optimal Operation Considering The Flow Routing

Energy conservation and emission reduction,promoting the energy structure adjustment,developing renewable energy and clean energy vigorously,implementing the development concept "Lucid waters and lush mountains are invaluable assets" is one of the strategic disposition of national energy development.As one of the clean energy which has mature development technology,hydropower performs important functions on our energy supply.With unceasing expansion of construction scale of hydropower engineering and buildings of big hydropower stations,the development of hydropower has entered a golden period,and the powerful energy supply will assure the socialist modernization.So the optimal operation of the hydropower stations has been built,improving the efficiency of water resource utilization and finalizing production-planning accuracy is one of the important part of reservoirs operation.The short-term cascade reservoir optimal operation(SCROO)always guides the actual operation of cascade hydropower stations.SCROO has played an important role on the reservoir operation.Starting with the operation theory,model,and solving algorithms,this paper makes further research on the hot and different issues in SCROO.Some innovative progress has been obtained on the issues like the flow connection between the downstream reservoir and upstream reservoir,the solution of optimal problems do not satisfy the "Principe of Optimality",and the solution of "curse of dimensionality".And this paper uses case studys of cascade hydro-power stations consisting of Jinxi,Jindong and Guandi in Yalong river basin.The main contributions of this dissertation are briefly summarized as follows:(1)Short-term cascade reservoir operation considering the flow routing.Because of the short operation period,the flow propagation has a significant impact on SCROO.As a result,the flow propagation should be considered in SCROO.The flow from upstream reservoir to downstream reservoir which propagates in the natural channel can be generalized as not only transposition but also attenuation.In the researches of SCROO,the flow delay time is usually simplified:take upstream reservoir outflow for a certain time as downstream reservoir's inflow equally.In order to get the relative accurate inflow series of downstream reservoir,the paper tries to adopt the Muskingum model to simulate the inflow of the downstream reservoir instead of the easier processing in most papers of SCROO,making more accurate operation plan and reducing the hydropower loss.(2)A coupled algorithm with Muskingum method and DPSA has been presented.Muskingum method uses the outflow series of upstream reservoir to simulate the inflow series of downstream reservoir.Taking advantage of the known of the other reservoirs'capacity change process in DPSA,this paper couple the DPSA and Muskingum method and uses the coupled algorithm to solve the SCROO model considering the flow routing,making the cascade reservoirs generation plan.It is shown in a case study of cascade reservoir consist of Jindong and Guandi.This paper uses DPSA which only consider the water delay and the coupled algorithm to solve the SCROO.The operation result is given and analyzed.(3)Multi-dimensional Dynamic Programming Model is presented.Considering the attenuation effect of the flow between the cascade reservoirs,the SCROO do not satisfy the "Principe of Optimality" anymore,so the Dynamic Programming(DP)is no longer applicable,then the paper proposes a new model:Multi-dimensional Dynamic Programming Model.In the model,multi-stages' outflow of upstream reservoir is taken into account at the same time and then inflow of downstream reservoir can be calculated by the Muskingum model,which can include much more flow information than DP's,and the inflow of downstream reservoir will be closer to the actual flow.It is shown in a case study of cascade hydro-power stations consisting of Jindong and Guandi in Yalong river basin.By comparing the operation result of the model and DP,the operation strategy of the model can gain further benefits than DP's in actual operation.(4)Hydropower Station Output Function(HSOF)and optimized DP named HFDP are presented.with the increase of the reservoirs' number,DP will face problems like long computation time,large calculation scale,which is called 'curse of dimensionality'.Heuristic random search algorithms and improved DP algorithms can decrease the computation time but they can only get near-optimal solutions.By analyzing the principle of DP in ROO,this paper finds that DP involves complex iterative computation and repeated procedures,which is very time-consuming.Aiming at solving these problems,this paper proposes a new notion called Hydropower Station Output Function(HSOF)and uses it to optimize and improve traditional DP,which can reduce the iterative computation and repeated procedures then improve computational efficiency.This paper takes "Jinguan" as examples for and cascade reservoir operation optimization.Case presents that the improved DP based on HSOF can reduce the programming complexity of DP,thus effectively alleviates the time-consuming problem and in the meantime,keeps the global convergence feature of DP(5)The short-term cascade reservoirs operation model considering the power grid's constraints is presented.The short-term reservoir operation,which is concerned with the execution of the long-term operation plan in hydropower station,is one important process during the station operation.In order to ensure the the stable operation of power grid when execute the generation plan made by the short-term reservoir operation,this paper adds the grid's constraints to the traditional operation model and set up a new short-term reservoir operation model taken the maximization generation of hydropower as the objective function.This paper solves the model using the POA to seek the best operation way on the basis of the safety and stabilization of the power grid.This paper takes the"Jinguan" of Yalong River as an example to set up a short-term reservoir operation model concerned the power grid's constraints and compares the operation result of traditional model.